Originally Posted by k_bojar

FDR = final drive ratio

the mathematical equation goes like this (spur/pinion) x the internal ratio of the car (diff gear/puller / center pulley/bevel gear)

so on the V2 - the internal ratio is 2.055 (37t pulley/18t center pulley)

so, if you had a 95t spur, and put a 48t pinion on your car you'd get the following:

(95/48) * 2.055 = 4.07 FDR

basically the lower the number, the more top-end the car will have, but you'll loose some bottom end grunt (power off turns)...however, this is all related to the track you're running...if you are running on a real small, tight (lots of turns) track, a FDR like my example above, could possibly overheat and destroy your motor - so on a track like that, you'd want a higher FDR

make sense?